Tunicamycin-Induced ER Stress is Accompanied with Oxidative Stress via Abrogation of Sulfur Amino Acids Metabolism in the Liver.
Int J Mol Sci
; 19(12)2018 Dec 18.
Article
em En
| MEDLINE
| ID: mdl-30567393
ABSTRACT
Endoplasmic reticulum (ER) stress is involved in non-alcoholic fatty liver disease (NAFLD), but the relationship between oxidative stress, another well-known risk factor of NAFLD, and ER stress has yet to be elucidated. In this study, we treated mice with tunicamycin (TM) (2 mg/kg body weight) for 48 h to induce ER stress in the liver and examined the metabolic pathway that synthesizes the endogenous antioxidant, glutathione (GSH). Tunicamycin (TM) treatment significantly increased mRNA levels of CHOP and GRP78, and induced lipid accumulation in the liver. Lipid peroxidation in the liver tissue also increased from TM treatment (CON vs. TM; 3.0 ± 1.8 vs. 11.1 ± 0.8 nmol MDA/g liver, p < 0.001), which reflects an imbalance between the generation of reactive substances and antioxidant capacity. To examine the involvement of GSH synthetic pathway, we determined the metabolomic changes of sulfur amino acids in the liver. TM significantly decreased hepatic S-adenosylmethionine concentration in the methionine cycle. The levels of cysteine in the liver were increased, while taurine concentration was maintained and GSH levels profoundly decreased (CON vs. TM; 8.7 ± 1.5 vs. 5.4 ± 0.9 µmol GSH/g liver, p < 0.001). These results suggest that abnormal cysteine metabolism by TM treatment resulted in a decrease in GSH, followed by an increase in oxidative stress in the liver. In HepG2 cells, decreased GSH levels were examined by TM treatment in a dose dependent manner. Furthermore, pretreatment with TM in HepG2 cells potentiated oxidative cell death, by exacerbating the effects of tert-butyl hydroperoxide. In conclusion, TM-induced ER stress was accompanied by oxidative stress by reducing the GSH synthesis, which made the liver more susceptible to oxidative stress.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Estresse Oxidativo
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Fator de Transcrição CHOP
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Hepatopatia Gordurosa não Alcoólica
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Proteínas de Choque Térmico
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Fígado
Tipo de estudo:
Risk_factors_studies
Limite:
Animals
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Humans
Idioma:
En
Ano de publicação:
2018
Tipo de documento:
Article